APPLICANT'S ABSTRACT: Ethanol is a potent teratogen for the developing central nervous system (CNS). Prenatal ethanol exposure disrupts the proliferative activities of neuronal precursors and glia. Analysis of cell cycle kinetics indicate that both in vivo and in vitro ethanol treatment prolong the duration of cell cycle and in particular, the length of the G1- phase. The movement of cells through the cell cycle is regulated by a family of protein kinases known as cyclin-dependent kinases (CDKs). The activity of CDKs is regulated positively by cyclins, and negatively by CDK inhibitors (CKIS). CDK activity is controlled by extracellular signal-related kinases (ERKs). Ethanol can affect ERK activity. We hypothesize (1) that ethanol- induced inhibition of cell proliferation results from disruptions of CDK systems, and (2) that ERK mediates ethanol-induced alternations in CDK systems. The proposed project will rely on two in vitro models, B104 neuroblastoma cells and primary cortical astrocyytes, to examine the effects of ethanol on the ERK and CDK systems. The studies will investigate the effects of ethanol on the activity of ERKS. Other experiments will examine the effects of ethanol (a) on the expression and activity of G1-phase-specific CDKs and (b) the effects of ethanol on the balance between positive (cyclins) and negative (CKIS) regulators of CDKs. Each of the experiments on ethanol-induced alterations of CDK system will be performed with cells in which ERK activity is intact and depleted (using a specific ERK blocker). Thus, we will be able to determine whether the CDK activity is ERK-dependent. Together, the battery of studies represents a systematic investigation of the effects of ethanol on CDK systems and related signal pathways. It will not only explore the mechanism(s) underlying ethanol-induced cell cycle damage, but also provide an important insight into the regulation of cell cycle in neural cells.